Prepared surface of polyolefin fabric,asphalt and rubber crumb



Dec. 15, 1970 H. L. DRAPER ETAL PREPARED SURFACE OF POLYOLEFIN FABRIC,ASPHALTAND RUBBER CRUMB Filed Nov. 1, 1967 leuaam CRl/MB-IS ASPHAlT-MP01 YOL EFM/ FABRIC *13 A5 PHAL 7'! 2 PRIME COAT-l0 GROUND INVENTORS ATTORNEVS 3,547,674 PREPARED SURFACE OF POLYOLEFIN FABRIC,

ASPHALT AND RUBBER CRUMB Homer L. Draper, Dale F. Levy, and Duane W.Gagle, Bartlesville, Okla., assignors to Phillips Petroleum Company, acorporation of Delaware Filed Nov. 1, 1967, Ser. No. 679,674 Int. Cl.EOlc /22; B44d 1/16 US. Cl. 11732 4 Claims ABSTRACT OF THE DISCLOSURE Asurface is prepared composed of asphalt, a polyolefin fabric and rubbercrumb. The rubber crumb is atop the polyolefin fabric which isimpregnated with the asphalt. In one method embodying the invention, acoating of asphalt is sprayed onto the place or area to be surfaced.Then a layer of a polypropylene fabric is placed into the freshlysprayed asphalt. A second coating of asphalt is sprayed onto the fabricfollowing which rubber crumbs are distributed over the fresh asphalt ata rate of 3-6 pounds per square yard. The surface of the rubber is nowcovered with a partition agent such. as talc or portland cement and thesystem then compacted with a roller to orient the rubber crumbs. Aperiodof curing of approximately 4 to 8 hours is allowed and the area isthen ready for service as on a playground, running track or protectivecovering.

SURFACE AND METHOD OF PREPARING THE SAME This invention relates to aprepared surface. It also relates to the preparation of such a surface.

In one of its concepts the invention provides a prepared surfacecomposed of asphalt, a polyolefin fabric and crumb rubber. In another ofits concepts, the invention provides a method for preparing a surfacecomposed, as stated, by laying asphalt upon an area, then setting apolyolefin fabric, e.g., polypropylene, into the asphalt, then coveringthe thus layed fabric with additional asphalt and finally covering withcrumb rubber. In a further concept of the invention, the method providesfor compacting, rolling, or pressing the crumb rubber together with theimpregnated fabric. In a further concept of the invention, it providesfor compacting the crumb rubber with aid of a partition agent placedthereon to facilitate the compacting and orienting of the crumb rubberduring compacting.

It is known to treat a cotton fabric, cloth or fibrous material with anasphalt cut-back oil and to then spread sand on top of the thus treatedfabric. It is also known to cover a fibrous fabric material with a goodcoating of asphalt and cut stone which is then rolled and finally givena top coat of asphalt. Further, it is known to prepare a preformed unitadapted for use in flooring or paving which includes a mixture of aplastic binder such as asphalt and reinforcing fibers of asbestos rag orthe like and particles of stone or other anti-skid or wear-resistingmaterials imbedded in the base thereof. Further, it is known to imbedthe anti-skid material in a suitable based material while undercompression from all directions. Further, it is known to provide afoundation layer of a thermoresponsive material to which flakes of apigmented thermoresponsive material are applied in random manner andbonded thereto.

It is an object of this invention to provide a surfacing. It is anotherobject of this invention to provide a method for surfacing. It is afurther object of this invention to provide a surfacing systempossessing improved elasticity,

United States Patent 0 3,547,674 Patented Dec. 15, 1970 ice improvedcohesiveness, and improved wearing qualities. A still further object ofthe invention is to provide an anti-skid surface system for playgrounds,running tracks, athletic fields, driveways, runways or to protect othersurfaces from the elements.

Other aspects, concepts and objects of the invention are apparent from astudy of this disclosure, the drawing and the appended claims.

According to the present invention there is provided a prepared surfacecomposed of asphalt, a polyolefin fabric and crumb rubber. Stillaccording to the invention, there is provided a method for thepreparation of a surface which comprises impregnating with an asphalt, apolyolefin fabric spreading crumb rubber upon the thus impregnatedfabric and then pressing the crumb rubber against said impregnatedfabric thus to orient and flatten the same to said surface.

In the drawing there is shown a cross-sectional view of the nowpreferred embodiment of the invention in which asphalt has been sprayedonto a place, a polypropylene fabric has been set into the asphalt, moreasphalt has been sprayed onto the polypropylene fabric, crumb rubber ata rate in the approximate range of from 3 to 6 pounds per square yardhas been added, the area has then been lightly dusted with talc and thenrolled.

The polyolefin now preferred is polypropylene. A fabric now preferred isknown as Locktuft. 1 The fabric can be woven or nonwoven and can becomposed of a mass of fibrils as obtained when fibrillating a polyolefinweb.

We have found that polyolefin fabric, particularly polypropylene fabricas here described, which is a high density polypropylene, possesses thequality of binding together with the asphalt and with the crumb rubberto produce a durable, elastic, laminate system or surface which thoughit is made to yield, especially as the strata therebelow yields, willshow good wearing qualities, including good cohesiveness.

Asphalts which can be used can be various. The asphalt ordinarily isused as a spray and suitably is in the form of an emulsion. In one formof the invention one layer of asphalt will be composed of cationicasphalt and another layer will be composed of anionic asphalt. Thisresults in better bindings in some applications. Usually cationicasphalt emulsion is used. The physical properties of the asphalt will beadjusted to thoroughly wet the polyolefin fabric as well as thesubstrata. Further, the asphalt and the crumb rubber will be so selectedas to yield good cohesiveness and cure, which can be assisted by radiantheating.

Thus, the crumb rubber can be compounded with additives causing it tomeld with the asphalt and to form a continuum therewith. Included in theadditives can be a vulcanizing agent which will vulcanize or furthervulcanize the crumb rubber, as the case may be.

After compacting of the system upon the area upon which it is to be usedor which it is to protect, there will be allowed usually a curingperiod, which depending upon the nature of the materials used may be ofthe order of several hours, say about 4 to about 8 hours.

As partition agents for the compacting, there may be used those agentswhich enhance the orienting of the crumb rubber particles. Such agentsinclude talc, limestone dust, Portland cement, etc.

Depending upon the pressure of the compacting, the particles of crumbrubber will orient and will also flatten so as to provide a somewhatrough, yet continuous surface, as stated, having good wear qualities aswell as resiliency.

The standard or conventional construction for playgrounds, driveways,etc., requires: 2 to 4 inches of 1 Trademark.

3 crushed, graded, gravel laid on the ground; a prime coat about A3 inchthick of such as a medium curing (MC) cutback asphalt added thereto; anda top surface of 1 to 3 inches of asphaltic concrete.

The construction of this invention, for equivalent service, requires(see the figure): a prime coat about Ms inch thick of such as a mediumcuring (MC) cut-back asphalt applied to the ground 11; a layer ofcationic asphalt emulsion 12 applied in the amount of 0.2 to 0.5,usually 0.3, gallon per square yard of surface; the fabric 13, about to/8 inch thick Locktuft; a second layer of cationic asphalt emulsion 14in the same quantity as above; and a layer of rubber crumb 15 ranging insize (shortest dimension) of about inch to (longest dimension) of about/2 inch in the quantity of 3 to 6 pounds per square yard, usually about4 pounds per square yard. Prior to rolling the surface, talc (such asabout 100 to 400 mesh) is dusted over the surface of the construction inorder to prevent pickup of materials by the roller.

Without the use of the rubber crumb, the coefficient of friction of theasphalt surface is tool low for safe and proper usage. When usingconventional stone chips to attempt to increase the coefficient offriction of the surface, an accidental fall results in cuts andabrasions, including severe floor burn. With the rubber crumb, thecoefiicient of friction of the surface is so increased that slipping issubstantially completely avoided, and an accidental fall causes no cuts,and rarely results in any floor burn.

It has been found that the polypropylene fabric can hold up to aboutfour times its weight of asphaltic materials, as compared with a feltpaper, which holds only about twice its weight of asphalt, and withcotton or Wool fabrics, which are poorer yet. Further, the paper, cottonfibers, and animal hair fibers tend to disintegrate in use. Thepolypropylene fabric does not disintegrate in use, since it isrot-resistant.

The crumb rubber which can be used to produce the surface system of theinvention can be a synthetic butadiene-styrene crumb rubber containingcarbon black. A typical crumb comprised seventy-five parts of butadiene,twenty-five parts styrene, and fifty parts of carbon black (by weight).Other known rubbers can be used. Also, there can be included in therubber oil extenders, curing agents, vulcanizing agents, pigments, etc.,depending upon the service to which the surface is to be exposed. Therubber particles are pressed or rolled (oriented) into the asphaltsurface. In some operations, vulcanization is accelerated by applicationof radiant heat. In some applications, it is believed that there is achemical union, in part, between 2 Trademark.

the asphalt and the rubber or components in the rubber. Also, it isfound that rolling can cause the rubber to entangle or to intermesh withthe fabric to result in a rigid holding of the rubber particles by thefabric, resulting in extra-long service of the system.

Reasonable variation and modification are possible within the scope ofthe foregoing disclosure, the drawing and the appended claims to theinvention, the essence of which is that there has been provided asurfacing system composed of asphalt, a polyolefin fabric and crumbrubber; that a method has been supplied for preparing such a surface byapplying asphalt to an area upon which the surface is to be prepared,setting a polyolefin fabric into the asphalt, assuring that the fabricis thoroughly impregnated with the asphalt and covering the same withcrumb rubber which then is compacted and oriented onto the thusimpregnated fabric; and that in a preferred embodiment of the invention,the fabric is composed of polypropylene.

We claim:

1. A prepared surface composed of an adherent mass of an asphalt, apolyolefin fabric and a crumb rubber, the asphalt being coated on thepolyolefin fabric and the rubber adhering to the asphalt coating.

2. A surface according to claim 1 wherein the polyolefin fabric isimpregnated with the asphalt and the crumb rubber is atop theimpregnated fabric.

3. A surface according to claim 2 wherein the crumb rubber is orientedand flattened to the surface top.

4. A surface according to claim 3 wherein the polyolefin fabric iscomposed essentially of a polypropylene.

References Cited UNITED STATES PATENTS 1,113,116 10/1914 Goldberg 117-91,925,282 9/1933 tRobinson 117 21 2,159,586 5/1939 Greider et al. 117 322,321,396 6/1943 Koch 117-9 2,353,027 7/1944 Goodwin 94-9 2,871,7742/1959 Johnson 117 33x 3,143,422 8/1964 Caldwell 117-138.8X 3,166,6081/1965 Natta et al. 117-13'8.8X 3,205,093 9/1965 Lynch '117-138.8

WILLIAM D. MARTIN, Primary Examiner US. Cl. XiR.

